Beat egg whites until soft peaks form. Gradually add 1 cup sugar, beating until stiff but not dry. Blend in 1 teaspoon lemon juice. Grease 23 cm pie pan generously. Spoon meringue mixture into pan and with tablespoon push mixture up around edges to form pie shell. Bake at 90ºC 2 hours. Cool. To make filling, beat egg yolks with half cup sugar, lemon peel and juice until light. Cook, stirring, in top of double boiler over boiling water until thickened. Remove from heat and cool thoroughly. Fold in half of whipped cream. Turn into meringue crust and refrigerate at least 2 hours to set. Fold powdered sugar into remaining whipped cream and spread over chilled pie.